Propargylated aminoindans, processes for preparation, and uses thereof

ABSTRACT

This invention provides compounds having the structure: 
     
       
         
         
             
             
         
       
         
         wherein R 1  is methyl and R 2  is H, or R 1  is ethyl and R 2  is hydroxymethyl; 
         R 3  is H or propargyl; and 
         R 4  is either H or t-butyloxycarbonyl;
 
or an enantiomer or a pharmaceutically acceptable salt thereof. This invention further provides the use of a therapeutically effective amount of such compounds to treat a subject afflicted with a psychiatric disorder, Parkinson&#39;s disease, Alzheimer&#39;s disease, dementia, or a neurological disorder.

This application claims benefit of U.S. Provisional Application No. 60/776,386, filed Feb. 24, 2006, the contents of which are hereby incorporated by reference.

Throughout this application various publications, published patent applications, and patents are referenced. The disclosures of these documents in their entireties are hereby incorporated by reference into this application in order to more fully describe the state of the art to which this invention pertains.

BACKGROUND OF THE INVENTION

PCT International Application Publication No. WO 98/27055 (U.S. Pat. No. 6,303,650, issued Oct. 16, 2001 to Chorev) discloses molecules of general formula I:

wherein when a is 0, b is 1 or 2; when a is 1, b is 1, m is from 0-3, X is O or S, Y is halogeno, R₁ is hydrogen or C₁₋₄ alkyl, R₂ is hydrogen, C₁₋₄ alkyl, or optionally substituted propargyl and R₃ and R₄ are each independently hydrogen, C₁₋₈ alkyl, C₆₋₁₂ aryl, C₆₋₁₂ aralkyl, each optionally substituted. These compounds have been disclosed as monoamine oxidase inhibitors that additionally inhibit acetylcholinesterase, and are useful to treat depression, Attention Deficit Disorder (“ADD”), Attention Deficit and Hyperactivity Disorder (“ADHD”), Tourett's Syndrome, Alzheimer's Disease and other. dementias such as senile dementia, dementia of the Parkinson's type, vascular dementia and Lewy body dementia.

One of the compounds disclosed in WO 98/27055 is R(+)-6-(N-methyl, N-ethyl-carbamoyloxy)-N′-propargyl-1-aminoindan, also known as (3R)-3-(prop-2-ynylamino)-2,3,-dihydro-1H-inden-5-yl ethyl methyl carbamate (compound 76 in Table 5). In addition, salts are disclosed, including the ½ L-tartrate salt. This salt has been given the nonproprietary name ladostigil tartrate. Its CAS registry number is 209394-46-7. Disclosed herein are novel related compounds.

SUMMARY OF THE INVENTION

The subject invention provides a pharmaceutical composition comprising a compound having the structure:

-   wherein R₁ is methyl and R₂ is H, or R₁ is ethyl and R₂ is     hydroxymethyl; and -   R₃ is H or propargyl; or -   an enantiomer or a pharmaceutically acceptable salt thereof;     and a pharmaceutically acceptable carrier.

The subject invention also provides a method of treating a subject afflicted with a psychiatric disorder, Parkinson's disease, Alzheimer's disease, dementia, or a neurological disorder comprising administering to the subject a therapeutically effective amount of a compound having the structure:

-   wherein R₁ is methyl and R₂ is H, or R₁ is ethyl and R₂ is     hydroxymethyl; and -   R₃ is H or propargyl; or     an enantiomer or a pharmaceutically acceptable salt thereof.

The subject invention also provides a process for making a compound having the structure:

-   wherein R₁ is methyl and R₂ is H, or R₁ is ethyl and R₂ is     hydroxymethyl; and -   R₃ is H or propargyl;     comprising administering to a human subject an amount of     R(+)-6-(N-methyl, N-ethyl-carbamoyloxy)-N′-propargyl-1-aminoindan,     or a pharmaceutically acceptable salt thereof.

The subject invention also provides a process for making a compound having the structure:

comprising

-   -   a) reacting a compound having the structure:

-   or a salt thereof with paraformaldehyde and water so as to make the     compound, and     -   b) recovering the compound from the reaction mixture.

The subject invention also provides a process for making a compound having the structure:

comprising

-   a) reacting a compound having the structure:

-   wherein R is a protecting group, with paraformaldehyde and water in     an organic solvent in the presence of an acidic moiety so as to     produce a product; -   b) reacting the product of step a) with an acidifying agent so as to     thereby remove the protecting group and make the compound; and -   c) recovering the compound made in step b).

The subject invention also provides a process for making a compound having the structure:

-   wherein R₁ is H or propargyl, comprising -   a) reacting a compound having the structure:

-   -   wherein R₁ is H or propargyl and R₂ is a protecting group,

-   with methylamine to form a product having the structure:

-   b) reacting the product formed in step a) with an acidifying agent     so as to make the compound; and -   c) recovering the compound made in step b).

The subject invention provides an isolated compound having the structure:

-   wherein R₁ is methyl and R₂ is H, or R₁ is ethyl and R₂ is     hydroxymethyl; -   R₃ is H or propargyl; and -   R₄ is either H or t-butyloxycarbonyl; or     an enantiomer or a pharmaceutically acceptable salt thereof.

The subject invention also provides a method for assaying the amount of ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester in a sample comprising the steps:

-   a) obtaining a sample; and -   b) determining the amount of ethyl-hydroxymethyl-carbamic acid     3-(prop-2-ynylamino)-indan-5-yl ester in the sample.

The subject invention also provides a method for assaying the amount of methyl-carbamic acid 3-R-amino-indan-5-yl ester in a sample comprising the steps:

-   a) obtaining a sample; and -   b) determining the amount of methyl-carbamic acid     3-R-amino-indan-5-yl ester in the sample.

The subject invention also provides a method for assaying the amount of methyl-carbamic acid 3-(prop-2-ynylamino)-indan-5-yl ester in a comprising the steps:

-   a) obtaining a sample; and -   b) determining the amount of methyl-carbamic acid     3-(prop-2-ynylamino)-indan-5-yl ester in the sample.

The subject invention also provides a use of a compound having the structure:

-   wherein R₁ is methyl and R₂ is H, or R₁ is ethyl and R₂ is     hydroxymethyl; and -   R₃ is H or propargyl; or     an enantiomer or a pharmaceutically acceptable salt thereof, for the     preparation of a medicament for treating a subject afflicted with a     psychiatric disorder, Parkinson's disease, Alzheimer's disease,     dementia, or a neurological disorder.

DETAILED DESCRIPTION OF THE INVENTION

The subject invention provides a pharmaceutical composition comprising a compound having the structure:

-   wherein R₁ is methyl and R₂ is H, or R₁ is ethyl and R₂ is     hydroxymethyl; and -   R₃ is H or propargyl; or -   an enantiomer or a pharmaceutically acceptable salt thereof;     and a pharmaceutically acceptable carrier. The pharmaceutical     composition can comprise any one of the specific compounds described     herein.

In an embodiment of the pharmaceutical composition, the compound has the structure:

In another embodiment of the pharmaceutical composition, the compound has the structure:

In another embodiment of the pharmaceutical composition, the compound has the structure:

In another embodiment of the pharmaceutical composition the form of the composition is a solid.

The subject invention also provides a method of treating a subject afflicted with a psychiatric disorder, Parkinson's disease, Alzheimer's disease, dementia, or a neurological disorder comprising administering to the subject a therapeutically effective amount of a compound having the structure:

-   wherein R₁ is methyl and R₂ is H, or R₁ is ethyl and R₂ is     hydroxymethyl; and -   R₃ is H or propargyl; or     an enantiomer or a pharmaceutically acceptable salt thereof.

In an embodiment of the method the subject is afflicted with a psychiatric disorder.

In another embodiment of the method the psychiatric disorder may be depression, generalized anxiety disorder, obsessive-compulsive disorder, panic attacks and panic disorder, phobic disorder, stress disorder, depersonalized disorder, dissociative amnesia, dissociative fugue, dissociative identity disorder, personality disorder, delusional disorder, schizoaffective disorder, schizophrenia, schizophreniform disorder, substance-induced psychotic disorder, gender identity disorder, paraphilias, body dysmorphic disorder, hypochondriasis, Munchausen's syndrome, pain disorder, or somatization disorder.

Depression is an illness that involves the body, mood and thoughts and comes in a variety of types, including, major depression, dysthymia and bipolar disorder. Major depression is manifested by a combination of symptoms that interfere with the ability to work, study, sleep, eat, and enjoy pleasurable activities. Such a disabling episode of depression may occur only once but more commonly occurs several times in a lifetime. Dysthymia is a less severe type of depression involving long-term, chronic symptoms that do not disable a person, but prevent one from functioning well or feeling good. Another type of depression is bipolar disorder (manic-depressive illness). It is not as common as other depressive disorders. Individuals with bipolar disorder experience cycling mood changes involving severe highs (mania) and lows (depression). Depressive disorders are primarily treated medically with selective serotonin reuptake inhibitors (SSRIs) and monoamine oxidase inhibitors (MAOIs).(National Institute of Mental Health, “Depression” 2002)

In an embodiment of the method, the subject is afflicted with a neurological disorder.

In another embodiment of the method the neurological disorder may be epilepsy, narcolepsy, amyotrophic lateral sclerosis (“ALS”), memory disorders, panic, post-traumatic stress disorder (“PTSD”), sexual dysfunction, attention deficit and hyperactivity syndrome (“ADHD”), attention deficit disorder, or Tourette's syndrome.

In another embodiment of the method, the subject is afflicted with dementia.

In another embodiment the dementia may be static dementia, Alzheimer's-type dementia, senile dementia, presenile dementia, progressive dementia, vascular dementia or Lewy body dementia.

In another embodiment of the method, the subject is afflicted with Alzheimer's disease.

In another embodiment of the method, the subject is afflicted with Parkinson's disease.

In another embodiment of the method, the subject is afflicted with depression.

In yet another embodiment of the method, the compound has the structure:

In yet another embodiment of the method, the compound has the structure:

In yet another embodiment of the method, the compound has the structure:

The subject invention also provides a process for making a compound having the structure:

-   wherein R₁ is methyl and R₂ is H, or R₁ is ethyl and R₂ is     hydroxymethyl; and -   R₃ is H or propargyl;     comprising administering to a human subject an amount of     R(+)-6-(N-methyl, N-ethyl-carbamoyloxy)-N′-propargyl-1-aminoindan,     or a pharmaceutically acceptable salt thereof.

Although the compound can be recovered from the subject, production of the compound in the subject may be the goal. This process can be used to produce any one of the specific compounds described herein by the selection of appropriate starting materials.

In an embodiment of the process, the compound administered to the human subject is R(+)-6-(N-methyl, N-ethyl-carbamoyloxy)-N′-propargyl-1-aminoindan ½ tartrate.

The subject invention also provides a process for making a compound having the structure:

comprising

-   a) reacting a compound having the structure

-   or a salt thereof with paraformaldehyde and water so as to make the     compound, and -   b) recovering the compound from the reaction mixture.

The compound produced by this process can be any one of the compounds described herein, including ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester, methyl-carbamic acid 3-R-amino-indan-5-yl ester or methyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester.

In an embodiment of the process, the reaction of step a) is performed in the presence of an acidifying agent.

In another embodiment of the process, the acidifying agent is HCl, acetic acid, or a cation exchange resin.

In yet another embodiment of the process, recovery in step b) is performed using chromatography, extraction or flash column chromatography.

The subject invention also provides a process for making a compound having the structure:

comprising

-   a) reacting a compound having the structure

-   wherein R is a protecting group, -   with paraformaldehyde and water in an organic solvent in the     presence of an acidic moiety so as to produce a product; -   b) reacting the product of step a) with an acidifying agent so as to     thereby remove the protecting group and make the compound; and -   c) recovering the compound made in step b).

In specific embodiments of the process, the acidic moiety can be HCl or a cation exchange resin, or the HCl anion of the starting material of step a), as exemplified in Example 3d, infra.

In an embodiment of the process, the protecting group is t-butyloxycarbonyl.

In another embodiment of the process, the organic solvent is dioxane or tetrahydrofuran.

In yet another embodiment of the process, the acidifying agent is HCl in ethyl acetate.

The subject invention also provides a process for making a compound having the structure:

-   wherein R₁ is H or propargyl, comprising -   a) reacting a compound having the structure

-   -   wherein R₁ is H or propargyl and R₂ is a protecting group,     -   with methylamine to form a produce having the structure

-   b) reacting the product formed in step a) with an acidifying agent     to make the compound; and -   c) recovering the compound made in step b).

In an embodiment of the process, R₂ is t-butyloxycarbonyl.

In another embodiment of the process, the acidifying agent is HCl in ethyl acetate.

In yet another embodiment of the process, prior to step a) a compound of having the structure:

-   wherein R₁ is H or propargyl and R₂ is a protecting group, is     reacted with chloromethyl chloroformate to produce the compound as     which the reaction of step a) is performed.

The subject invention provides an isolated compound having the structure:

-   wherein R₁ is methyl and R₂ is H, or R₁ is ethyl and R₂ is     hydroxymethyl;     -   R₃ is H or propargyl; and     -   R₄ is either H or t-butyloxycarbonyl; or     -   an enantiomer or a pharmaceutically acceptable salt thereof.

In an embodiment of the compound, R₄ is H.

In another embodiment, the compound has the structure:

an enantiomer or a pharmaceutically acceptable salt thereof.

In another embodiment, the compound is ethyl-hydroxymethyl-carbamic acid 3-(prop-2-ynylamino)-indan-5-yl ester fumarate (2:1).

In another embodiment, the compound is ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester, or a pharmaceutically acceptable salt thereof.

In another embodiment, the compound is ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester fumarate (2:1).

In yet another embodiment, the compound has the structure:

an enantiomer or a pharmaceutically acceptable salt thereof.

In yet another embodiment, the compound is methyl-carbamic acid 3-amino-indan-5-yl ester hydrochloride.

In yet another embodiment, the compound is methyl-carbamic acid 3-R-amino-indan-5-yl ester, or a pharmaceutically acceptable salt thereof.

In yet another embodiment, the compound is methyl-carbamic acid 3-R-amino-indan-5-yl ester hydrochloride.

In a further embodiment, the compound has the structure:

an enantiomer or a pharmaceutically acceptable salt thereof.

In a further embodiment, the compound is methyl-carbamic acid 3-(prop-2-ynylamino)-indan-5-yl ester hydrochloride.

In a further embodiment, the compound is methyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester, or a pharmaceutically acceptable salt thereof.

In a further embodiment, the compound is methyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester hydrochloride.

In yet a further embodiment, the compound has the structure:

-   wherein R₄ is t-butyloxycarbonyl.

In yet a further embodiment of the compound, R₁ is methyl, R₂ is H, and R₃ is propargyl.

In yet a further embodiment of the compound, R₁ is methyl, R₂ is H, and R₃ is H.

In yet a further embodiment of the compound, R₁ is ethyl, R₂ is hydroxymethyl, and R₃ is propargyl.

The subject invention also provides a method for assaying the amount of ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester in a sample comprising the steps:

-   a) obtaining a sample; and -   b) determining the amount of ethyl-hydroxymethyl-carbamic acid     3-(prop-2-ynylamino)-indan-5-yl ester in the sample.

The subject invention also provides a method for assaying the amount of methyl-carbamic acid 3-R-amino-indan-5-yl ester in a sample comprising the steps:

-   a) obtaining a sample; and -   b) determining the amount of methyl-carbamic acid     3-R-amino-indan-5-yl ester in the sample.

The subject invention also provides a method for assaying the amount of methyl-carbamic acid 3-(prop-2-ynylamino)-indan-5-yl ester in a sample comprising the steps:

-   a) obtaining a sample; and -   b) determining the amount of methyl-carbamic acid     3-(prop-2-ynylamino)-indan-5-yl ester in the sample.

The subject invention also provides use of a compound having the structure:

-   wherein R₁ is methyl and R₂ is H, or R₁ is ethyl and R₂ is     hydroxymethyl; and -   R₃ is H or propargyl; or     an enantiomer or a pharmaceutically acceptable salt thereof, for the     preparation of a medicament for treating a subject afflicted with a     psychiatric disorder, Parkinson's disease, Alzheimer's disease,     dementia, or a neurological disorder.

In an embodiment of the use, the subject is afflicted with a psychiatric disorder.

In another embodiment of the use the psychiatric disorder may be depression, generalized anxiety disorder, obsessive-compulsive disorder, panic attacks and panic disorder, phobic disorder, stress disorder, depersonalized disorder, dissociative amnesia, dissociative fugue, dissociative identity disorder, personality disorder, delusional disorder, schizoaffective disorder, schizophrenia, schizophreniform disorder, substance-induced psychotic disorder, gender identity disorder, paraphilias, body dysmorphic disorder, hypochondriasis, Munchausen's syndrome, pain disorder, or somatization disorder.

In an embodiment of the use, the subject is afflicted with a neurological disorder.

In another embodiment of the use, the neurological disorder is epilepsy, narcolepsy, amyotrophic lateral sclerosis (“ALS”), memory disorders, panic, post-traumatic stress disorder (“PTSD”), sexual dysfunction, attention deficit and hyperactivity syndrome (“ADHD”), attention deficit disorder, or Tourette's syndrome.

In another embodiment of the use, the subject is afflicted with dementia.

In another embodiment of the use dementia is static dementia, Alzheimer's-type dementia, senile dementia, presenile dementia, progressive dementia, vascular dementia or Lewy body dementia.

In another embodiment of the use, the subject is afflicted with Alzheimer's disease.

In another embodiment of the use, the subject is afflicted with Parkinson's disease.

In another embodiment of the use, the subject is afflicted with depression.

In yet another embodiment of the use, the compound has the structure:

In yet another embodiment of the use, the compound has the structure:

In yet another embodiment of the use, the compound has the structure:

The enzyme monoamine oxidase (“MAO”) plays an essential role in the metabolic degradation of important amine neurotransmitters including dopamine, serotonin and noradrenaline. Thus, agents that inhibit MAO are of potential therapeutic benefit for a variety of neurological disease indications, including Parkinson's disease, Alzheimer's disease, depression, epilepsy, narcolepsy, amyothrophic lateral sclerosis (“ALS”), etc. (Szelnyi, I.; Bentue-Ferrer et al.; Loscher et al.; White et al.; U.S. Pat. No. 5,744,500).

Acetylcholinesterase (“AChE”) inhibition is a route implicated in certain neurological disorders, but is a different route from the route of MAO inhibition.

The disclosed compounds are both MAO inhibitors and AChE inhibitors.

The compounds of the present invention may be prepared as pharmaceutical compositions. Such compositions may comprise the compound and/or pharmaceutically acceptable salts thereof, together with pharmaceutically acceptable carriers and/or excipients. Pharmaceutically acceptable salts include, but are not limited to, the mesylate, maleate, fumarate, tartrate, hydrochloride, hydrobromide, esylate, p-tolunesulfonate, benzoate, acetate, phosphate and sulfate salts.

The compositions may be prepared as medicaments to be administered orally, parenterally, rectally or transdermally. Suitable forms for oral administration include tablets, compressed or coated pills, dragees, sachets, hard or soft gelatin capsules, sublingual tablets, syrups and suspensions; for parenteral administration the invention provides ampoules or vials that include an aqueous or non-aqueous solution or emulsion; for rectal administration there are provided suppositories with hydrophilic or hydrophobic vehicles; and for topical application as ointments and transdermal delivery there are provided suitable delivery systems as known in the art.

Specific examples of pharmaceutical acceptable carriers and excipients that may be used to formulate oral dosage forms of the present invention are described, e.g., in U.S. Pat. No. 3,903,297 to Robert, issued Sep. 2, 1975. Techniques and compositions for making dosage forms useful in the present invention are described-in the following references: 7 Modern Pharmaceutics, Chapters 9 and 10 (Banker & Rhodes, Editors, 1979); Pharmaceutical Dosage Forms: Tablets (Lieberman et al., 1981); Ansel, Introduction to Pharmaceutical Dosage Forms 2nd Edition (1976); Remington's Pharmaceutical Sciences, 17th ed. (Mack Publishing Company, Easton, Pa., 1985); Advances in Pharmaceutical Sciences (David Ganderton, Trevor Jones, Eds., 1992); Advances in Pharmaceutical Sciences Vol 7. (David Ganderton, Trevor Jones, James McGinity, Eds., 1995); Aqueous Polymeric Coatings for Pharmaceutical Dosage Forms (Drugs and the Pharmaceutical Sciences, Series 36 (James McGinity, Ed., 1989); Pharmaceutical Particulate Carriers: Therapeutic Applications: Drugs and the Pharmaceutical Sciences, Vol 61 (Alain Rolland, Ed., 1993); Drug Delivery to the Gastrointestinal Tract (Ellis Horwood Books in the Biological Sciences. Series in Pharmaceutical Technology; J. G. Hardy, S. S. Davis, Clive G. Wilson, Eds.); Modern Pharmaceutics Drugs and the Pharmaceutical Sciences, Vol 40 (Gilbert S. Banker, Christopher T. Rhodes, Eds.).

Tablets may contain suitable binders, lubricants, disintegrating agents, coloring agents, flavoring agents, flow-inducing agents, and melting agents. For instance, for oral administration in the dosage unit form of a tablet or capsule, the active drug component can be combined with an oral, non-toxic, pharmaceutically acceptable, inert carrier such as lactose, gelatin, agar, starch, sucrose, glucose, methyl cellulose, dicalcium phosphate, calcium sulfate, mannitol, sorbitol, microcrystalline cellulose and the like. Suitable binders include starch, gelatin, natural sugars such as glucose or beta-lactose, corn starch, natural and synthetic gums such as acacia, tragacanth, or sodium alginate, povidone, carboxymethylcellulose, polyethylene glycol, waxes, and the like. Lubricants used in these dosage forms include sodium oleate, sodium stearate, sodium benzoate, sodium acetate, sodium chloride, stearic acid, sodium stearyl fumarate, talc and the like. Disintegrators include, without limitation, starch, methyl cellulose, agar, bentonite, xanthan gum, croscarmellose sodium, sodium starch glycolate and the like.

As used herein, an “isolated” compound is a compound that is separate from the mixture of components normally found in or excreted by an animal, for example a human, such as cells, organs, blood, saliva, urine, etc. Thus, an isolated compound is not part of the mixture which constitutes animal, blood, saliva, urine, etc., nor is it part of an animal cell or organ. An isolated compound may be obtained by separation from the animal, or, alternatively, by a chemical synthesis process.

As used herein, a “pharmaceutically acceptable” carrier is one that is suitable for use with humans and/or animals without undue adverse side effects (such as toxicity, irritation, and allergic response) commensurate with a reasonable benefit/risk ratio, and is not blood or blood plasma.

EXPERIMENTAL DETAILS Example 1 Preparation of ethyl-carbamic acid 3-R-(N-Boc-prop-2-ynylamino)-indan-5-yl ester

Ethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester HCl was prepared as described in U.S. Pat. No. 6,303,650 (compound 56 in table 5) using the R-enantiomer starting material. Ethyl-carbamic acid 3-R-prop-2-ynylamino-indan-5-yl ester HCl (0.5 g, 1.70 mmol) was converted to its free base by dissolving it in a mixture of water (20 ml), 30% ammonium hydroxide (20 ml), and dichloromethane (30 ml). The layers were separated, and the aqueous layer was re-extracted with dichloromethane (8×30 ml). The combined organic layers were dried (Na₂SO₄), and evaporated to dryness at reduced pressure to give 400 mg of the free base as a viscous oil. The free base (0.40 g, 1.55 mmol) was dissolved in absolute ethanol (20 ml), and a solution of di-tert-butyl dicarbonate (0.35 g, 1.60 mmol) in ethanol (10 ml) was added. The mixture was stirred at 25° C. under nitrogen for 24 h, and the solvent was removed at reduced pressure. Hexane (50 ml) was added to the residue, the mixture was stirred at room temperature for 30 min, and the hexane was decanted off. The hexane washing and decanting steps were repeated (5×30 ml), and the combined hexane washings were evaporated to dryness at reduced pressure. The residue was dried under vacuum for 24 h to give 550 mg (90%) of the title compound as an off-white solid.

Example 2 Preparation of ethyl-hydroxymethyl-carbamic acid 3-R-(N-Boc-prop-2-ynylamino)-indan-5-yl ester

A mixture of ethyl-carbamic acid 3-R-(N-Boc-prop-2-ynylamino)-indan-5-yl ester prepared in Example 1 (1.08 g, 3 mmol), paraformaldehyde (180 mg, 6 mmol), pretreated Lewatit SPC 108 (a polystyrene sulfonic acid cation exchange resin,) (180 mg, 0.75 mequiv. of H⁺), dioxane (6 ml), and water (21.6 mg, 1.2 mmol) was stirred and heated at 60° C. under nitrogen for 24 hr. The mixture was cooled to 25° C. and filtered. The residue on the filter was washed with dioxane, and the filtrate was evaporated to dryness at reduced pressure. The crude residue which resulted after evaporation of the dioxane was purified by flash column chromatography (elution with ethyl acetate/hexane 70/30) to give 450 mg (38% yield) of the title compound as a viscous oil.

¹³C-NMR (CD₃CN) δ 14.19 and 15.03 (MeCH₂), 28.45 (Me₃C), 30.30 (C-2), 31.37 (C-1), 34.11 and 35.42 (NCH₂CCH), 42.40 and 42.62 (MeCH₂), 62.21 and 63.71 (C-3), 72.01 and 72.30 (NCH₂OH, NCH₂CCH), 80.95 (Me₃C), 82.48 (NCH₂CCH), 118.30 (C-4), 122.34 (C-6), 126.22 (C-7), 141.44 (C-3a), 151.43 (C-5), 155.80 (NCO).

Example 3a Preparation of ethyl-hydroxymethyl-carbamic acid 3-R-prop-2-ynylamino-indan-5-yl ester

A solution of ethyl-hydroxymethyl-carbamic acid 3-R- (N-Boc-prop-2-ynylamino)-indan-5-yl ester prepared in Example 2 (150 mg, 0.386 mmol) and 2N HCl in ethyl acetate (20 ml, 40 mmol) was stirred at room temperature for 2 hr. The mixture was evaporated to dryness at reduced pressure, and the residue was treated with water (10 ml), dichloromethane (20 ml), and enough 5% sodium bicarbonate solution to bring the pH of the aqueous layer to 8.5-9.0. The layers were separated, and the aqueous layer was re-extracted with dichloromethane (4×15 ml). The organic layers were combined and evaporated to dryness to give 90 mg of a viscous oil. Purification by flash column chromatography gave 11 mg (9%) of the title compound (free base) (90% pure by NMR).

Example 3b Preparation of ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester

A mixture of ethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester HCl salt (5.0 g, 16.96 mmol), water (41.5 ml), paraformaldehyde (2.03 g, 67.6 mmol), and 1N HCl (9 ml, 9.0 mmol) was stirred and heated in a glass stoppered flask at 37-40° C. for 7 hours. The mixture was cooled in an ice bath, and water (40 ml) and dichloromethane (60 ml) were added. Saturated sodium bicarbonate (enough to bring the pH to 8.5-9.0) was added slowly while stirring. The two layers were separated, and the aqueous layer was re-extracted with dichloromethane (7×40 ml). The organic layers were combined, dried (sodium sulfate), filtered, and evaporated to dryness at 25° C. under vacuum to give 5.0 g of crude ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester as a white solid. This was stored in the freezer until purified by flash column chromatography as detailed below.

The eluting solution (3%EtOH/CHCl₃+NH₃) was prepared as follows:

A mixture of CHCl₃ (800 ml) and 25% NH₄OH (40 ml) was placed in a 1 L separatory funnel, shaken vigorously, left to stand (tightly sealed) for 1 hr, and the phases separated. Most of the organic phase (about 750 ml) was collected in an Erlenmeyer flask containing NaSO₄ (40 g), and the mixture filtered rapidly (gravitationally, through a cotton-filled funnel) into a measuring cylinder, to give about 720 ml of ammoniacal chloroform solution (pH=10), which was then transferred into a tightly sealed bottle. The appropriate amount of EtOH was then added to give the required 3% v/v solution.

A solution of crude ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester free base (5 g) in minimum amount of CHCl₃ was charged on a 4.5 cm wide column filled (35 cm height) with silica previously wetted with the above solution. Ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester was eluted by the same solution and monitored by TLC (run in the same medium and detected by UV plus ninhydrin), to give 3.3 g of a viscous colorless oil (68%) containing about 7% CHCl₃ (w/w, by NMR).

Spectral and analytical data of ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester:

¹H-NMR (CD₃CN, δ):

Major Rotamer:

1.18 (brt, J=7 Hz, 3H, MeCH2), 1.82 (m, 1H, H-2), 2.40 (m, 1H, H-2), 2.45 (t, J=2.5 Hz, 1H, NCH2CCH), 2.77 (brdt, J=15.5, 7 Hz, 1H, H-1), 2.94 (ddd, J=15.5, 8, 5 Hz, 1H, H-1), 3.40 (m, 2H, MeCH2), 3.44 (m, 2H, NCH2CCH), 4.31 (t, J=6.5 Hz, 1H, H-3), 4.88 (brs, 2H, NCH2OH), 6.92 (dd, J=8, 2 Hz, 1H, H-6), 7.04 (d, J=2 Hz, 1H, H-4), 7.21 (d, J=8 Hz, 1H, H-7) ppm.

Minor Rotamer:

1.26 (brt, J=7 Hz, 3H, MeCH2), 1.82 (m, 1H, H-2), 2.40 (m, 1H, H-2), 2.45 (t, J=2.5 Hz, 1H, NCH2CCH), 2.77 (brdt, J=15.5, 7 Hz, 1H, H-1), 2.94 (ddd, J=15.5, 8, 5 Hz, 1H, H-1), 3.44 (m, 2H, NCH2CCH), 3.50 (m, 2H, MeCH2), 4.31 (t, J=6.5 Hz, 1H, H-3), 4.78 (brs, 2H, NCH2OH), 6.92 (dd, J=8, 2 Hz, 1H, H-6), 7.04 (d, J=2 Hz, 1H, H-4), 7.21 (d, J=8 Hz, 1H, H-7) ppm.

¹³C-NMR (CD₃CN, δ:

Major Rotamer:

14.26 (MeCH₂), 30.53 (C-2), 34.62 (C-1), 36.65 (NCH₂CCH), 42.69 (MeCH₂), 62.87 (C-3), 72.07 (NCH₂OH), 72.35 (NCH₂CCH), 83.78 (NCH₂CCH), 118.83 (C-4), 121.99 (C-6), 126.03 (C-7), 141.74 (C-3a), 147.61 (C-7a), 151.21 (C-5) ppm.

Minor Rotamer:

15.09 (MeCH₂), 30.53 (C-2), 34.62 (C-1), 36.65 (NCH₂CCH), 42.44 (MeCH₂), 62.87 (C-3), 72.35 (NCH₂OH and NCH₂CCH), 83.78 (NCH₂CCH), 118.83 (C-4), 121.99 (C-6), 126.03 (C-7), 141.74 (C-3a), 147.61 (C-7a), 151.21 (C-5) ppm.

MS: 289 (MH⁺, 12.17), 234 (100), 216 (29.64), 133 (92.66).

Example 3c Preparation of ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester

A mixture of ethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester free base (80 mg, 0.31 mmol), water (0.8 ml), paraformaldehyde (40 mg, 4 eq), and AcOH (36 μl, 2 eq) was stirred and heated in a glass stoppered flask at 37-40° C. for 48 hr. Water (1 ml) and paraformaldehyde (30 mg) were added and the mixture stirred at the same temperature for additional 24 hr, at which point LC/UV analysis indicated about 50% of ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester (the rest being mostly starting ethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester.

Example 3d Preparation of ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester

A mixture of ethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester HCl salt (50 mg, 0.17 mmol), water (0.41 ml, 22.8 mmol) and paraformaldehyde (20.3 mg, 0.67 mmol) was stirred at 40° C. for 48 hours. HPLC of the reaction mixture indicated 63% of ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester (plus 24% of ethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester).

Example 3e Preparation of ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester

A mixture of ethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester HCl (223 mg, 0.75 mmol), paraformaldehyde (45 mg, 1.5 mmol), pretreated Lewatit SPC 108 (a polystyrene sulfonic acid cation exchange resin,) (45 mg, 0.19 mequiv. of H⁺), dioxane (3 ml), and water (6 mg, 0.33 mmol) was stirred and heated at 40° C. under nitrogen for 8 hr. The mixture was cooled to 25° C. and filtered. The residue on the Buchner funnel was washed with dioxane and the filtrate was evaporated to dryness at reduced pressure. The residue which resulted after the dioxane evaporation was treated with water (10 ml), dichloromethane (20 ml), and enough 5% sodium bicarbonate to bring the pH to 8.5-9.0. The layers were separated, and the aqueous layer was re-extracted with dichloromethane (4×15 ml). The combined organic layer was dried and evaporated to dryness at 25° C. under vacuum to give a viscous oil. HPLC analysis showed about 30-35% of ethyl-hydroxymethyl-carbamic acid 3-R-prop-2-ynylamino-indan-5-yl ester free base.

Example 3f Preparation of ethyl-hydroxymethyl-carbamic acid 3-S-(prop-2-ynylamino)-indan-5-yl ester

The title compound is prepared using the starting material ethyl-carbamic acid 3-S-(N-Boc-prop-2-ynylamino)-indan-5-yl ester according to the procedures described in Examples 1-3e.

Example 4 Preparation of ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester fumarate (2:1)

Fumaric acid (0.49 g, 4.25 mmol, 0.5 eq) was added to a solution of ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester free base (2.45 g, 8.5 mmol) in iPrOH (49 ml), and the resulting suspension slightly warmed for a few seconds by a heat gun. A white suspension was formed, and the mixture was stirred at room temperature for 1 hr, and cooled in an ice bath for 30 min. The suspension was filtered, washed with cold iPrOH and dried under vacuum overnight to give the title compound as a white solid (2.45 g, 7.1 mmol, 83%), mp: 114−6° C.

Spectral and analytical data of ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester fumarate (2:1):

¹H-NMR (D₂O, δ):

Major Rotamer:

1.18 (brt, J=7 Hz, 3H, MeCH₂), 2.28 (m, 1H, H-2), 2.58 (m, 1H, H-2), 2.96 (ddd, J=16, 9, 4 Hz, 1H, H-1), 2.99 (t, J=2.5 Hz, 1H, NCH₂CCH), 3.12 (dt, J=16, 8 Hz, 1H, H-1), 3.43 (brq, J=7 Hz, 2H, MeCH₂), 3.93 (m, 2H, NCH₂CCH), 4.92 (dd, J=8, 3 Hz, 1H, H-3), 5.0 (brs, 2H, NCH₂OH), 6.44 (s, 2H, fumarate-CH), 7.16 (dd, J=8, 2 Hz, 1H, H-6), 7.28 (d, J=2 Hz, 1H, H-4), 7.40 (d, J=8 Hz, 1H, H-7) ppm.

Minor Rotamer:

1.27 (brt, J=7 Hz, 3H, MeCH₂), 2.28 (m, 1H, H-2), 2.58 (m, 1H, H-2), 2.96 (ddd, J=16, 9, 4 Hz, 1H, H-1), 2.99 (t, J=2.5 Hz, 1H, NCH₂CCH), 3.12 (dt, J=16, 8 Hz, 1H, H-1), 3.56 (brq, J=7 Hz, 2H, MeCH₂), 3.93 (m, 2H, NCH₂CCH), 4.87 (brs, 2H, NCH₂OH), 4.92 (dd, J=8, 3 Hz, 1H, H-3), 6.44 (s, 2H, fumarate-CH), 7.16 (dd, J=8, 2 Hz, 1H, H-6), 7.28 (d, J=2 Hz, 1H, H-4), 7.40 (d, J=8 Hz, 1H, H-7) ppm.

¹³C-NMR (D₂O, δ):

Major Rotamer:

13.62 (MeCH₂), 29.51 (C-2), 29.81 (C-1), 34.89 (NCH₂CCH), 43.17 (MeCH₂), 62.23 (C-3), 71.46 (NCH₂OH), 73.86 (NCH₂CCH), 78.76 (NCH₂CCH), 119.52 (C-4), 124.52 (C-6), 127.19 (C-7), 135.93 (fumarate CH), 137.91 (C-3a), 143.72 (C-7a), 150.17 (C-5), 156.62 (NCO), 174.93 (fumarate CO₂).

Minor Rotamer

14.32 (MeCH₂), 29.51 (C-2), 29.81 (C-1), 34.89 (NCH₂CCH), 42.86 (MeCH₂), 62.23 (C-3), 71.71 (NCH₂OH), 73.86 (NCH₂CCH), 78.76 (NCH₂CCH), 119.52 (C-4), 124.52 (C-6), 127.19 (C-7), 135.93 (fumarate CH), 137.91 (C-3a), 143.72 (C-7a), 150.17 (C-5), 156.62 (NCO), 174.93 (fumarate CO₂) ppm.

MS: 289 (MH⁺, 6), 234 (100), 216 (30), 133 (71).

Elemental analysis: Calcd for C₃₂H₄₀N₄O₆.C₄H₄0₄: C, 62.42; H, 6.40; N, 8.09. Found: C,-62.30%, H-6.63%, N-7.85%.

Example 5 Preparation of carbonic acid 3-R-(N-Boc-amino)-indan-5-yl ester chloromethyl ester

3-R-(N-Boc-amino)-indan-5-ol was synthesized as described in U.S. Pat. No. 6,303,650, Column 6. A solution of 3-R-(N-Boc-amino)-indan-5-ol (15.0 g) and triethylamine (8.7 ml) in methylene chloride (60 ml) was added dropwise to a stirred and ice-cooled solution of chloromethyl chloroformate (8.16 g) in methylene chloride (20 ml). The mixture was stirred for 2 h at rt, washed with 5% NaHCO₃ solution and water, dried and evaporated to dryness. The residue was crystallized (toluene/hexane) to give 13.0 g (63.3%) of the title compound.

¹H NMR (DMSO-d₆, δ): 7.35 (d, 1H, NH), 7.30 (d, 1H, Ph), 7.08 (m, 2H, Ph), 6.0 (s, 2H, CH₂Cl), 4.95 (q, 1H, C3-H), 2.9−2.6 (m, 2H, Cl), 2.35 (m, 1H, C2-H), 1.82 (m, 1H, C2-H′), 1.40 (s, 9H, tBu) ppm.

Example 6 Preparation of methyl-carbamic acid 3-R-(N-Boc-amino)-indan-5-yl ester

Carbonic acid 3-R-(N-Boc-amino)-indan-5-yl ester chloromethyl ester prepared in Example 5 (12.6 g) was combined with ethanolic methylamine (14 ml of a 33% solution) in dioxane (110 ml) and was stirred at rt for 3 h and evaporated to dryness. The residue was dissolved in EtOAc (200 ml), and the solution was filtered, washed with water, dried and evaporated to dryness. The residue was crystallized from EtOAc/ether to give the title compound (10.3 g, 91.1%)

¹H NMR (DMSO-d₆, δ): 7.60 (m, 1H, NHMe), 7.33 (d, 1H, NHBoc), 7.20 (d, 1H, Ph), 6.90 (m, 2H, Ph), 4.95 (q, 1H, C3-H), 2.9−2.6 (m, 2H, Cl), 2.65 (d, 3H, Me), 2.35 (m, 1H, C2-H), 1.85 (m, 1H, C2-H′), 1.44 (s, 9H, tBu) ppm.

Example 7a Preparation of methyl-carbamic acid 3-R-amino-indan-5-yl ester HCl

A 10% solution of HCl in EtOAc (150 ml) was added to a solution of methyl-carbamic acid 3-R-(N-Boc-amino)-indan-5-yl ester prepared in Example 6 (10.3 g) in EtOAc (220 ml). The suspension was stirred at rt for 15 min, and the solid collected by filtration (7.03 g, 86.3%).

¹H NMR (DMSO-d₆, δ): 8.75 (br s, 3H, NH₃ ⁺), 7.70 (m, 1H, NHMe), 7.40 (s, 1H, Ph), 7.30 (d, 1H, Ph), 7.05 (d, 1H, Ph), 4.65 (br s, 1H, C3-H), 3.05 (m, 1H, C1-H), 2.80 (m, 1H, C1-H′), 2.65 (d, 3H, Me), 2.45 (m, 1H, C2-H), 2.05 (m, 1H, C2-H′).

Example 7b Preparation of methyl-carbamic acid 3-S-amino-indan-5-yl ester HCl

The title compound is prepared using the starting material 3-S-(N-Boc-amino)-indan-5-ol according to the procedures described in Examples 5-7a.

Example 8 Preparation of carbonic acid chloromethyl ester 3-R-(N-Boc-prop-2-ynylamino)-indan-5-yl ester

3-R-(N-Boc-prop-2-ynylamino)-indan-5-ol was prepared as described in PCT Application Publication No. WO 03/072055, FIG. 1. A solution of 3-R-(N-Boc-prop-2-ynylamino)-indan-5-ol (10.2 g) and triethylamine (3.74 g) in methylene chloride (30 ml) was added dropwise to a stirred and ice-cooled solution of chloromethyl chloroformate (4.8 g) in methylene chloride (35 ml). The mixture was stirred for 2 h at rt, washed with 5% NaHCO₃ solution and water, dried and evaporated to dryness to give 13.45 g (100%) of the title compound as an oil.

¹H NMR (DMSO-d₆, δ), mixture of two rotamers: 7.35 (d, 1H, Ph), 7.16 (d, 1H, Ph), 7.03 (s, 1H, Ph), 6.0 (s, 2H, CH₂Cl), 5.62, 5.20 (2 m, 1H, C3-H), 4.16, 3.88 (2m, 2H, CH₂CCH), 3.1 (s, 1H, CC≡H), 3.0 (m, 1H, C1-H), 2.84 (m, 1H, C1-H′), 2.45 (m, 1H, C2-H), 2.19 (m, 1H, C2-H′), 1.50, 1.20 (2s, 9H, tBu) ppm.

Example 9 Preparation of methyl-carbamic acid 3-R-(N-Boc-prop-2-ynylamino)-indan-5-yl ester

Carbonic acid chloromethyl ester 3-R-(N-Boc-prop-2-ynylamino)-indan-5-yl ester prepared in Example 8 (13.45 g) was combined with ethanolic methylamine (12.5 ml of a 33% solution) in dioxane (165 ml) and was stirred at rt for 2 h and evaporated to dryness. The residue was dissolved in EtOAc (200 ml), and the solution was filtered, washed with water, dried and evaporated to dryness. The residue was crystallized from ether/hexane to give the title compound (9.35 g, 77.3%).

¹H NMR (DMSO-d₆, δ), mixture of two rotamers: 7.55 (m, 1H, NH), 7.23 (d, 1H, Ph), 6.92 (d, 1H, Ph), 6.80 (s, 1H, Ph), 5.62, 5.20 (2m, 1H, C3-H), 4.16, 3.80 (2 m, 2H, CH₂CCH), 3.1 (s, 1H, CC≡H), 2.95 (m, 1H, C1-H), 2.78 (m, 1H, C1-H′), 2.65 (d, 3H, Me), 2.40, (m, 1H, C2-H), 2.15 (m, 1H, C2-H′), 1.50, 1.20 (2s, 9H, tBu) ppm.

Example 10a Preparation of methyl carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester HC1

A 10% solution of HC1 in EtOAc (100 ml) was added to a solution of methyl-carbamic acid 3-R-(N-Boc-prop-2-ynylamino)-indan-5-yl ester prepared in Example 9 (9.0 g) in EtOAc (90 ml). The suspension was stirred at rt for 15 min, and the solid collected by filtration (7.3 g, 98.6%).

¹H NMR (DMSO-d₆, δ): 10.3 (br s, 3H, NH₃ ⁺), 7.70 (m, 1H, NHMe), 7.50 (s, 1H, Ph), 7.30 (d, 1H, Ph), 7.05 (d, 1H, Ph), 4.80 (br s, 1H, C3-H), 3.95 (m, 2H, CH₂CCH), 3.75 (s, 1H, CC≡H), 3.10 (m, 1H, C1-H), 2.80 (m, 1H, C1-H′), 2.65 (d, 3H, Me), 2.45 (m, 1H, C2-H), 2.30 (m, 1H, C2-H′).

Example 10b Preparation of Methyl carbamic acid 3-S-(prop-2-ynylamino)-indan-5-yl ester HCl

Methyl carbamic acid 3-S-(prop-2-ynylamino)-indan-5-yl ester HCl was prepared from 3-S-(N-Boc-prop-2-ynylamino)-indan-5-ol according to the procedures described in Examples 8-10a.

In vitro Studies

Example 11 Inhibition of MAO Activity in Vitro

The MAO enzyme source was a homogenate of rat brain in 0.3M sucrose. The homogenate was diluted appropriately, and pre-incubated with serial dilutions of test compounds—diluted in phosphate buffer containing clogyline when 2-phenylethylamine (PEA) is the substrate, and diluted in phosphate buffer containing selegiline when 5-hydroxytryptamine (5-HT) is the substrate—for 60 minutes at 37° C. ₁₄C-Labeled substrates (PEA for MAO-B determination and 5-HT for MAO-A determination) were then added, and the incubation continued for a further 20 minutes (PEA) or 30 minutes (5-HT). Substrate concentrations used were 10 μM (PEA) and 100 μM (5-HT). Enzyme concentration was chosen so that not more than 10% of the substrate was metabolized during the course of the reaction. Deaminated products were extracted into toluene-ethyl acetate (1:1 v/v) containing 0.4% (w/v) 2,5-diphenyloxazole (ppo) prior to determination by liquid scintillation counting. Radioactivity in the eluate indicated the production of neutral and acidic metabolites formed as a result of MAO activity. Activity of MAO in the sample was expressed as a percentage of control activity in the absence of inhibitor after subtraction of appropriate blank values. The activity determined using PEA as substrate is referred to as MAO-B, and that determined using 5-HT as MAO-A.

The experiment was performed using three inhibitors: Ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester fumarate (2:1) (“R-HCPAI”), Methyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester hydrochloride (“R-MCPAI”), and Methyl-carbamic acid 3-R-amino-indan-5-yl ester hydrochloride (“R-MCAI”).

Concentrations of each inhibitor producing 50% inhibition of substrate metabolism (IC₅₀) were calculated from the inhibition curves, and are shown in Table 1.

TABLE 1 IC₅₀ for MAO-A IC₅₀ for MAO-B Inhibitor inhibition (μM) inhibition (μM) R-MCPAI 37 142 R-MCAI 32.2 >1000 R-HCPAI 414 599

Example 12a Inhibition of Acetylcholinesterase (AChE) Activity in vitro

Enzyme and Reagents

Recombinant human AChE (C-1682), acetylthiocholine iodide (AcTh, A5771), bovine serum albumin (BSA, A-2153), and 5,5′-dithiobis(2-nitrobenzoic acid) (DTNB, D8130) were obtained from Sigma-Aldrich Israel. AChE was found to be in a tetrameric form by sucrose gradient. AChE was dissolved in phosphate buffer pH 8.0 containing 0.01% sodium azide NaAz and 1 mM EDTA and diluted to give a concentration of 15 units/ml. This solution was divided into aliquots of 0.5 ml, which were stored at −70° C. until use.

Enzyme Inhibition

The inhibitory activity against AChE was determined by the method of Ellmann et al. (Biochemical Pharmacology, 1961 (7) 88-95) using AcTh as a substrate. To characterize the carbamoylation step, a traditional stopped time assay was performed, in which AChE was incubated at 37° C. with a minimum of 5 different concentrations of inhibitor in the assay buffer, and aliquots were transferred to an ELISA multiscan microplate reader (Labsystems) at various times for the determination of residual AChE activity, with Ascent PC software. The rate of reaction was measured at 412λ at 37° C. in 0.2 ml wells containing AChE 0.023 units per ml, DTNB 0.4-0.5 mM, AcTh 0.50 or 1 mM and BSA (0.05%) in 50 mM phosphate buffer as described above. Measurements were made every 5 min for up to 5 hours.

The experiment was performed using three inhibitors: Ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester fumarate (2:1) (“R-HCPAI”), Methyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester hydrochloride (“R-MCPAI”), and Methyl-carbamic acid 3-R-amino-indan-5-yl ester hydrochloride (“R-MCAI”).

The inhibition of AChE by carbamates involves the formation of a reversible complex (EOH.CX), followed by carbamoylation of the enzyme to form (EOC) and a leaving group (HX). The carbamoylated enzyme is then hydrolyzed by water to regenerate the free enzyme (EOH).

The formation of the reversible complex is represented by the equilibrium constant: K_(D). For the carbamoylation phase of the inhibition process the unimolecular rate constant is represented by k_(max), and the bimolecular rate constant by k_(i).

TABLE 2 Inhibitor k_(max) (min⁻¹) k_(i) (mM * min⁻¹) K_(D) (mM) R-MCPAI 0.435 13.00 ± 0.91  0.034 R-MCAI 1.63 76.9 ± 4.7  0.021 R-HCPAI 0.033 0.106 ± 0.008 0.306

This experiment shows that R-MCPAI and R-MCAI are potent inhibitors of acetylcholinesterase.

This experiment also shows that R-HCPAI is a weak inhibitor of acetylcholinesterase.

Example 12b Inhibition of Butyrylcholinesterase (BuChE) Activity in vitro

Enzyme and Reagents

BuChE from human serum (C-9971), butyrylthiocholine iodide (BuTh, B3253), bovine serum albumin (BSA, A-2153) 5,5′-dithiobis(2-nitrobenzoic acid) (DTNB, D8130) were obtained from Sigma-Aldrich Israel. BuChE was dissolved in phosphate buffer pH 8.0 containing 0.01% sodium azide (NaAz) and 1 mM EDTA and diluted to give a concentration of 35.9 units/ml. This solution was divided into aliquots of 0.5 ml, which were stored at −70° C. until use.

Enzyme Inhibition

The inhibitory activity against BuChE was determined by the method of Ellmann et al. (Biochemical Pharmacology, 1961 (7) 88-95) using BuTh as a substrate. To characterize the carbamoylation step, a traditional stopped time assay was performed, in which BuChE was incubated at 37° C. with a minimum of 5 different concentrations of inhibitor in the assay buffer, and aliquots were transferred to an ELISA multiscan microplate reader (Labsystems) at various times for the determination of residual BuChE activity, with Ascent PC® software. The rate of reaction was measured at 412λ at 37° C. in 0.2 ml wells containing AChE 0.023 units per ml, DTNB 0.4-0.5 mM, AcTh 0.50 or 1 mM and BSA (0.05%) in 50 mM phosphate buffer as described above. For all compounds measurements were made every 2 min for 15 min and then every 15 min for 3 hr.

The experiment was performed using three inhibitors: Ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester fumarate (2:1) (“R-HCPAI”), Methyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester hydrochloride (“R-MCPAI”), and Methyl-carbamic acid 3-R-amino-indan-5-yl ester (“R-MCAI”) hydrochloride.

The inhibition of BuChE by carbamates involves the formation of a reversible complex (EOH.CX), followed by carbamoylation of the enzyme to form (EOC) and a leaving group (HX). The carbamoylated enzyme is then hydrolyzed by water to regenerate the free enzyme (EOH).

The formation of the reversible complex is represented by the equilibrium constant: K_(D). For the carbamoylation phase of the inhibition process the unimolecular rate constant is represented by k_(max), and the bimolecular rate constant by k_(i).

TABLE 3 Inhibitor k_(max) (min⁻¹⁾ k_(i) (mM * min⁻¹) K_(D) (mM) R-MCPAI 0.65 ± 0.03 31.3 ± 2.0  0.021 ± 0.002 R-MCAI 0.516 ± 0.050 14.5 ± 0.42 0.036 ± 0.005 R-HCPAI 0.104 ± 0.043 0.936 ± 0.06  0.111 ± 0.05 

This experiment shows that R-MCPAI and R-MCAI are potent inhibitors of butyrylcholinesterase.

This experiment also shows that R-HCPAI is a weak inhibitor of butyrylcholinesterase.

Example 13 Use of Synthetic ethyl-hydroxymethyl-carbamic Acid 3-R-(Prop-2-ynylamino)-indan-5-yl ester fumarate (2:1) as a Reference Standard for Assay Determination of ethyl-hydroxymethyl-carbamic acid 3-R-(Prop-2-ynylamino)-indan-5-yl ester in Biological Samples

The objective of the method is the detection of ladostigil and its known metabolite ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester in plasma. The method consists of solid phase extraction (SPE) with both manual and automatic options for sample preparation and LC-MS/MS analysis. Ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester in plasma is quantified using ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester fumarate 2:1 analytical standard and its own isotopic internal standard (¹³C-ethyl-hydroxymethyl-carbamic acid 3-(prop-2-ynylamino)-indan-5-yl ester fumarate (2:1).

LC-MS/MS Conditions

LC-MS/MS analyses is carried out using a Perkin Elmer Sciex API 2000 mass spectrometer, which is connected to the HPLC system via a TIS interface operated at 350° C. The mass spectrometer is programmed to admit the protonated molecules [M+H]+ via the first quadropole filter (Q1), with collision-induced fragmentation at Q2. The product ion is monitored via Q3. The precursor and product ions are 289 and 133, respectively.

The LC conditions include Waters Symmetry C18 3.5 μ 2.1×50 mm column with Pre-column Filter 1/16″, Peek, 2 μm and mobile phase composition of acetonitrile, 0.1% formic acid and 1% THF in water in gradient mode up to 40% of acetonitrile content.

Sample Preparation

Plasma sample is spiked with Internal Standard, then centrifuged and the supernatant is diluted with 2% cc NH₄OH and 5% methanol in water (Solvent B). The volume of the sample is loaded on a STRATA X 33μ Polymeric Sorbent 30 mg/1 mL Extraction Cartridge, which is pre-conditioned first with methanol (Solvent A) and then with Solvent B. The cartridge is washed with Solvent B and sample is eluted with 2% glacial Acetic acid and 80% methanol in water (Solvent C). The eluted sample is evaporated at about 37° C. to dryness and reconstituted with 0.1% formic acid and 1% THF in water. The sample is then filtered through 0.2μ filter before injection into LC-MS/MS.

Quantification

The amount of ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester in plasma sample is quantified vs. plasma calibration curve of ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester and using its own isotopic internal standard.

Conclusion

Ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester has been found to be a metabolite of ladostigil in vivo. It can be used as a reference standard or marker in investigating the pharmacokinetics and metabolic profile of ladostigil.

In vivo Studies

Example 14 Chronic Administration of ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester fumarate (2:1) and Ladostigil Tartrate to Rats

30 rats were separated randomly into 5 testing groups of 6 rats each. Group 1 was the control group to which no drug was administered. Ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester fumarate (2:1) was administered to groups 2, 3, 4 in dosages of 150, 75, and 37.5 μmol/kg respectively, daily, perorally (“P.O.”) for seven consecutive days. Water was used as a vehicle.

Rats were sacrificed, out of sight of the other rats, 2 hours after the last administration. Brains were removed into Petri dishes on ice, the cerebellums were rolled out, and the brains cut into halves for analysis. Livers and intestines were removed for MAO determination. Organs were homogenated for enzyme inhibition analysis.

The MAO inhibition after administration of hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester fumarate (2:1) in various organs is listed in Table 4 calculated in percent relative to the control group.

TABLE 4 Dose in Brain Liver Duodenum μmol/kg MAO-A MAO-B MAO-A MAO-B MAO-A MAO-B 150 72 83 16 34 21 35 75 41 62 9 18 18 31 37.5 8 17 3 15 −25 7

The data indicates that administration of ethyl hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester fumarate (2:1) causes brain-selective MAO inhibition.

Example 15 Administration of Ladostigil Tartrate Tablets to Humans

Tablets were prepared through wet granulation using isopropanol. The tablets were made with the excipients listed in Table 5:

TABLE 5 Tablet Tablet Tablet equivalent equivalent equivalent to 20 mg to 50 mg to 80 mg ladostigil ladostigil ladostigil tartrate tartrate tartrate Excipient base base base Function Ladostigil 25.6 64.0 102.4 Drug tartrate Substance Mannitol 13.4 33.5 53.6 Filler USP/BP Pregelatinized 32.0 80.0 128.0 Disintegrant starch (starch 1500 NF) Syloid 244 1.8 4.5 7.2 Disintegrant (Colloidal and flowing Silicon agent Dioxide) Polividone 30 7.2 18.0 28.8 Binder (PVP) Mannitol 120.0 — — Filler granulate Stearic acid 4.0 4.0 6.4 Lubricant Talc 8.0 8.0 12.8 Lubricant Isopropyl q.s. q.s. q.s. alcohol Total tablet 212.0 212.0 339.2 weight Administration of Ladostigil Tartrate to Alzheimer's Disease Patients

8 patients, 7 female and 1 male, ages 62-81 with a median age of 68 and above with diagnosis of probable Alzheimer's disease according to DSM-IV (290.00 or 290.10) and NINCDS-ADRDA criteria were administered ladostigil tartrate according to the following schedule:

-   Week 1: 70 mg (50+20) once daily. -   Week 2: 70 mg (50+20) twice daily. -   Week 3-Week 9: 100 mg (50*2) twice daily.

4 patients (3 male and 1 female) aged 70 to 84 years old were in the placebo group.

Pharmacokinetic Analysis

Pharmacokinetic analysis was performed on Week 4 (maintenance analysis) and on Week 9 (termination analysis). At maintenance analysis, samples were collected pre-dose and at 0.25, 0.5, 1, 2, and 3 hours post-dose. At termination analysis, samples were collected pre-dose and at 0.25, 0.5, 1, 2, 3, 4 and 6 hours post-dose.

TABLE 6¹ Patient Number 1 2 3 4 5 6 7 8 MAO (T) (%) −55 −85  −98 −76 −89 −76 −54 −64 DHPG (T) (%) −63 −86 ND ND >−79 −73 −30 −13 AUC (ng * hr/mL) ladostigil (M) 314 589 1005 927 436 551 52 500 ladostigil (T) 246 2305 1449 482 398 901 118 350 MCPAI (M) 684 103 596 764 491 630 212 304 MCPAI (T) 493 789 621 487 551 947 584 343 MCAI (M) 62 121 172 191 171 144 213 86 MCAI (T) 570 733 958 672 895 964 186 426 HCPAI (M) 1662 600 2287 2152 1702 1891 519 1513 HCPAI (T) 1295 3101 2520 1744 1651 2399 1037 1337 C_(max) (nmol/mL) ladostigil (M) 1.1 1.2 3.5 3.9 1.4 1.5 0.2 1.7 ladostigil (T) 0.7 3.8 3.9 1.6 1.0 2.5 0.4 1.3 MCPAI (M) 1.8 0.3 1.2 3.0 1.5 1.3 0.5 0.7 MCPAI (T) 1.3 1.0 1.0 1.1 1.3 1.3 1.0 0.6 MCAI (M) 0.1 0.2 0.3 0.3 0.3 0.3 0.4 0.2 MCAI (T) 0.2 0.2 0.3 0.2 0.4 0.3 0.2 0.2 HCPAI (M) 3.6 1.5 3.7 7.0 4.7 4.0 1.2 3.3 HCPAI (T) 3.2 3.9 3.9 3.9 3.7 3.2 2.1 2.6 ¹R-CPAI = ladostigil; HCPAI= R-HCPAI= Ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester; MCPAI= R-MCPAI= Methyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester; and MCAI= R-MCAI= Methyl-carbamic acid 3-R-amino-indan-5-yl ester.

Mean C_(max) after dosing and mean C_(min) (concentration at pre-dose) of ladostigil tartrate and 3 of its metabolites at maintenance analysis (M) and at termination analysis (T) were determined and are listed in Table 6, as well as half life (t_(1/2)) at termination. The concentration measurements are expressed in nmol/ml and the t_(1/2) is expressed in terms of hours.

TABLE 7 Analyte C_(min) (M) C_(min) (T) C_(max) (M) C_(max) (T) t_(1/2) R-CPAI 0.0164 0.0109 2.02 1.88 1.08 R-HCPAI 0.0232 0.0137 3.63 3.30 1.03 R-MCPAI 0.0174 0.0132 1.29 1.07 1.39 R-MCAI 0.153 0.139 0.270 0.261 8.09 MAO-B Inhibition

Monoamine oxidase B inhibition in plasma samples from the aforementioned patients was determined at baseline and at termination analysis (see Example 11, supra, for determination of MAO B inhibition in samples). The percent inhibition was calculated for each patient, and the mean percent inhibition was then determined to be 75% (standard deviation=16) at the termination analysis.

HPLC Analysis of MAO-A Inhibition

Decrease of 3,4-dihydroxyphenylglycol (“DHPG”) in plasma is indicative of monoamine oxidase inhibition, especially in the brain. DHPG plasma concentrations were measured in 6 of the aforementioned patients at baseline and at termination analysis, using HPLC equipped with an electrochemical detector.

The decrease in DHPG concentration in the six patients was determined. The average decrease in DHPG concentration was determined to be 57% with a standard deviation of 29.

Discussion

The data show that the analytes were present at pre-dose (which corresponds to 12 hours after the previous dose) both at maintenance and at termination analyses.

There is evidence of significant MAO-B inhibition.

Cholinesterase inhibition at pre-dose administration both at maintenance and at termination analyses was also evident. 

1. A pharmaceutical composition comprising an isolated compound having the structure:

wherein R₁ is ethyl and R₂ is hydroxymethyl; and R₃ is H or propargyl; or an enantiomer or a pharmaceutically acceptable salt thereof; and a pharmaceutically acceptable carrier.
 2. The pharmaceutical composition of claim 1, wherein the compound has the structure:


3. An isolated compound having the formula ethyl-hydroxymethyl-carbamic acid 3-(prop-2-ynylamino)-indan-5-yl ester fumarate (2:1).
 4. An isolated compound having the formula ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester, or a pharmaceutically acceptable salt thereof.
 5. An isolated compound having the formula ethyl-hydroxymethyl-carbamic acid 3-R-(prop-2-ynylamino)-indan-5-yl ester fumarate (2:1).
 6. An isolated compound having the structure:

wherein R₄ is t-butyloxycarbonyl, R₁ is ethyl, R₂ is hydroxymethyl and R₃ is H or propargyl.
 7. The compound of claim 6, wherein R₃ is propargyl. 